Variable state length initialization

ABSTRACT

Through the use of a variable state length initialization, both the transmitter and the receiver can have control of the length of one or more initialization states. For example, a transmitter can send information, such as a message, to the receiver at the commencement of, during initialization or prior to entering a variable length initialization state. The information can specify, for example, a minimum length of an initialization state as needed by the transmitter.

RELATED APPLICATION DATA

[0001] This application claims the benefit of and priority under 35U.S.C. §119(e) to U.S. patent application Ser. No. 60/296,697, filedJun. 7, 2001, entitled “Variable State Length Initialization,” which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The systems and methods of this invention generally related tocommunications systems. In particular, the systems and methods of thisinvention relate to providing a variable state length initialization.

[0004] 2. Description of Related Art

[0005] Multicarrier modulation, which is also known as DiscreteMultitone Transmission (DMT), transceivers step a through a number ofinitialization states prior to entering steady-state communication or“showtime.” In particular, these various initialization states includechannel discovery, transceiver training, channel analysis, and the like.These various initialization states allow, for example, thedetermination of transmitter power levels, line characteristics,training of receiver function such as equalizers or echo cancellers, orany other feature necessary to establish communication, or to exchangeparameters and settings, between transceivers.

SUMMARY OF THE INVENTION

[0006] DSL (Digital Subscriber Line) modems use variable lengthinitialization states for ADSL communications. The ITU ADSL StandardsG.992.1 and G.992.2, incorporated herein by reference in their entirety,specify operation of conventional ADSL systems. For example, in“Multi-Company Proposal for Initialization,” incorporated herein byreference in its entirety, the C-REVERB1 initialization state and theR-REVERB3 initialization state have a variable length. The length of astate is defined as the number of DMT symbols transmitted in that statewhere DMT symbols are also known as multicarrier symbols. The length ofC-REVERB1 is controlled by the ATU-R (ATU-R—ADSL TransceiverUnit—Remote) and the length of R-REVERB3 is controlled by the ATU-C(ADSL Transceiver Unit—Central Office). In this example, the ATU-Ctransmitter continues to sends C-REVERB1 until the ATU-C receiverdetects R-REVERB2 sent from the ATU-R. Likewise, the ATU-R transmittercontinues to send R-REVERB3 until the ATU-R receiver detects C-REVERB2sent from the ATU-C transmitter. For example, when the ATU-C receiverhas received the R-REVERB3 signal for a sufficient amount of time, theATU-C transmitter sends the C-REVERB2 signal to the ATU-R which oncedetected by the ATU-R receiver causes the ATU-R transmitter to exit theR-REVERB3 state. Likewise, when the ATU-R receiver has received theC-REVERB1 signal for a sufficient amount of time, the ATU-R transmittersends the R-REVERB2 signal to the ATU-C which once detected by the ATU-Creceiver causes the ATU-C transmitter to exit the R-REVERB3 state.

[0007] It is important for the ATU-R receiver and the ATU-C receiver tocontrol the length of the states because the ATU-C receiver uses theR-REVERB3 signals and the ATU-R receiver uses the C-REVERB1 signals toperform adaptive signal processing algorithms such as, for example,equalizer training and frame synchronization. In general, this method ofhaving an ATU receiver control the length of an initialization state isused in the ITU standards for ADSL G.992.2 and G.992.1.

[0008] However, at least one problem associated with this method is thatit does not provide the ATU transmitter with the ability to control thelength of the states. This is problematic, for example, because oftenthe ATU transmitters may use these signals to also perform localadaptive signal processing, adaptive analog processing functions, or thelike. For example, the ATU-C transmitter may use the C-REVERB1 signalsto train a local, either analog or digital, echo canceller. In thisexample, it is important that the ATU-C maintain control of the lengthof the state, since the ATU-C may not have enough time to complete theecho canceller training if it is determined and regulated by the ATU-R.

[0009] Accordingly, an exemplary embodiment of this invention allows,for example, both the ATU transmitter and the ATU receiver to havecontrol of the length of one or more initialization states. For example,an ATU transmitter can send information, such as a message, to the ATUreceiver prior to entering or during a variable length initializationstate. The information can specify, for example, the minimum length ofthe initialization state as needed by the ATU transmitter. As is done inconventional ADSL modems, the ATU receiver controls the length of thestate by sending a pre-defined signal to the other ATU when the ATUreceiver wishes to terminate the state.

[0010] Using the above example, based on the C-REVERB1 state, prior toentering or during the C-REVERB1 state, the ATU-C would send a messageto the ATU-R indicating the minimum length of the state “MinState.” Forexample, the ATU-C could indicate that MinState equals 1000 DMT symbolsfor C-REVERB1. In this case, the ATU-R would wait at least 1000 DMTsymbols before the ATU-R transmitter would send R-REVERB2 to the ATU-C,and thus terminating the CREVERB1 state.

[0011] Aspects of the invention relate to multicarrier modulationcommunications.

[0012] Additional aspects of the invention relate to varying the lengthsof initialization states in multicarrier communication system.

[0013] Additional aspects of the invention relate to ATU-C and ATU-Rcontrolled initialization state lengths.

[0014] Aspects of the invention further relate to transmitter controlledinitialization state lengths.

[0015] Aspects of the invention further relate to receiver controlledinitialization state lengths

[0016] Aspects of the invention additionally relate to ATU transmitterand/or receiver controlled initialization state lengths.

[0017] Aspects of the invention also relate to exchanging informationbetween transceivers defining state lengths.

[0018] Aspects of the invention also relate to advancing to a nextinitialization state based at least on the completion of a variablestate length initialization procedure.

[0019] These and other features and advantages of this invention aredescribed in, or are apparent from, the following detailed descriptionof the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The embodiments of the invention will be described in detailed,with reference to the following figures, wherein:

[0021]FIG. 1 is a functional block diagram illustrating an exemplarycommunication system according to this inventions;

[0022]FIG. 2 is a functional block diagram illustrating exemplarycommunications between two modems according to this invention;

[0023]FIG. 3 is a functional block diagram illustrating exemplarycommunications between two modems according to a second embodiment ofthis invention;

[0024]FIG. 4 is a functional block diagram illustrating exemplarycommunications between two modems according to a third embodiment ofthis invention;

[0025]FIG. 5 is a flowchart outlining an exemplary method of performingvariable state length initialization according to this invention; and

[0026]FIG. 6 is a flowchart outlining a second exemplary embodiment ofperforming variable state length initialization according to thisinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0027]FIG. 1 illustrates an exemplary communication system 10. Inparticular, the communication system 10 comprises a first transceiver100 and a second transceiver 200, connected by link 5. The transceiver100 comprises a state length determination module 110, a state lengthverification module 120, a memory 130 and a message module 140. Thetransceiver 200 comprises a state length determination module 210, astate length verification module 220, a memory 230 and a message module240.

[0028] The exemplary systems and methods of the invention will bedescribed in relation to a subscriber line, such as a digital subscriberline communication system. However, to avoid unnecessarily obscuring thepresent invention, the following description omits well-known structuresand devices that may be shown in block diagram form or otherwisesummarized. For the purposes of explanation, numerous specific detailsare set forth in order to provide a thorough understanding of thepresent invention. It should be appreciated however that the presentinvention may be practiced in variety of ways beyond these specificdetails. For example, the systems and methods of this invention cangenerally be applied to any type of communications system includingwireless communications systems, such as wireless LANs, for examplebased on the IEEE802 systems, powerline communications, or any other orcombination of systems that uses mulitcarrier communications or any formof modulation that has initialization states whose lengths arecontrolled by the transceivers.

[0029] Furthermore, while the exemplary embodiments illustrated hereinshow the various components of the communication system collocated, itis to be appreciated that the various components of the system can belocated at distant portions of a distributed network, such as atelecommunications network and/or the Internet, or within a dedicatedvariable state length initialization system. Thus, it should beappreciated that the components of the communication system can becombined into one or more devices or collocated on a particular node ofa distributed network, such as a telecommunications network. As will beappreciated from the following description, and for reasons ofcomputational efficiency, the components of the communication system canbe arranged at any location within a distributed network withoutaffecting the operation of the system.

[0030] Furthermore, it should be appreciated that the various linksconnecting the elements can be wired or wireless lengths, or acombination thereof, or any other know or later developed element(s)that is capable of supplying and/or communicating data to and from theconnected elements. Additionally, the term module as used herein canrefer to any know or later developed hardware, software or combinationof hardware and software that is capable of performing the functionalityassociated with that element.

[0031] The communication system 10 in FIG. 1 illustrates twotransceivers 100 and 200, such as an ATU-C and ATU-R. Communicationsbetween the two transceivers occurs over link 5. However, prior tosteady-state communication between the two transceivers 100 and 200, aninitialization must be performed.

[0032] In particular, as discussed above, initialization is used totrain the transceiver which allows, for example, various parameters tobe detected and identified, signal processing functions to be trained,communication details between the two transceivers established, or thelike. Certain initialization states however require a certain number ofDMT symbols to be sent and/or received to satisfactorily complete thetraining function of an initialization state.

[0033] The exemplary operational embodiments illustrated in FIG. 1 willbe discussed in relation to an embodiment where the transceiver 100 isan ATU-C and the transceiver 200 is ATU-R. In the exemplary operationalembodiments, the protocols and methods are used to control the length ofstates where the ATU-C is the transmitting transceiver and the ATU-R isthe receiving transceiver. Such an example was described above inrelation to the control of the length of the C-REVERB1. Furthermore, theexemplary embodiment will be discussed in relation to the transceiver100 determining the minimum number of DMT symbols for the selectedstate, or, alternatively, the transceiver 200 determining the minimumnumber of DMT symbols for the selected state, or, alternatively, both ofthe transceiver 100 and the transceiver 200 determining the minimumnumber of DMT symbols for the selected state and monitoring the numberof received or transmitted DMT symbols as discussed hereinafter.

[0034] In particular, in operation, the state length determinationmodule 110 determines the minimum number of DMT symbols for the selectedstate, if any. Based on the determined MinState value, the messagemodule 140 forwards, via communication link 5, the MinState value 50 tothe transceiver 200. The transceiver 200, in cooperation with the statelength verification module 220 and the memory 230, monitors the receivedDMT symbols from the transceiver 100. Upon the state length verificationmodule 220 receiving at least the minimum number of specified DMTsymbols, the state length verification module 220 authorizes thetransceiver 200 to send a signal to the transceiver 100 such than whenthe signal is detected by the transmitter 100, the transceiver 100 willexit the current initialization state and transition to a newinitialization state. For example, the transceiver 200 and thetransceiver 100 can be preprogrammed to automatically enter a nextinitialization state based on the signal. Alternatively, the transceiver200 can forward a message, via link 5, to the transceiver 100 requestinga next initialization state to be entered.

[0035] Alternatively, the transceiver 200 can specify a MinState value25 for a particular initialization state. In particular, the statelength determination module 210 determines the minimum number of DMTsymbols for a selected state (MinState). Then, in cooperation with themessage module 240, information identifying the MinState value isforwarded, via link 5, to the transceiver 100 and, for example, storedin memory 130. Then, in cooperation with the state length verificationmodule 120, the transceiver 100 monitors the number of DMT symbolstransmitted to the transceiver 200 associated with the currentinitialization state. Upon the state length verification module 120transmitting at least the number of specified DMT symbols, the statelength verification module 120 authorizes the transceiver 100 to send asignal to the transceiver 200 that when detected by the receiver of thetransceiver 200 will indicate to the transceiver 200 that the currentinitialization state has been terminated and transition to a newinitialization state is commencing.

[0036]FIG. 2 illustrates the communications exchanged according to anexemplary embodiment of this invention based on the exemplary C-REVERB1state discussed above. In particular, the ATU-C sends information, suchas a message or identifier, identifying the MinState value to the ATU-Rindicating the minimum length of the state. For example, the ATU-C couldsend information indicating that the MinState value is equal to 1000 DMTsymbols for the C-REVERB1 state 250. In this exemplary case, the ATU-Rwould be required to, for example, wait at least 1000 DMT symbols beforethe ATU-R transmitter could send R-REVERB2 to the ATU-C. The forwardingof the R-REVERB2 to the ATU-C would thus terminate the CREVERB1 state.

[0037] Alternatively, as illustrated in FIG. 3, the ATU-R receiver maysend the desired length of the state to the ATU-C transmitter and theATU-C transmitter may terminate the state by, for example, sending aknown signal, such as a signal with reverse polarity (inverted) ascompared to the signal sent in the state that is being terminated, tothe ATU-R receiver.

[0038] Using the C-REVERB1 state from the example above, the ATU-R wouldsend information, such as an identifier or a message, to the ATU-Cindicating the minimum length of the state 260, e.g. the MinState value.For example, the ATU-R could indicate that the MinState value equals1000 DMT symbols for C-REVERB1. In this case, the ATU-C would berequired to wait at least 1000 DMT symbols before the ATU-C transmittercould send a known signal, e.g., C-SEGUE1, to the ATU-R, and thusterminate the C-REVERB1 state.

[0039] Alternatively still, FIG. 4 illustrates an exemplary embodimentin which both the ATU transmitter and the ATU receiver send the desiredlength of the states 270 and 280 to each other. In this exemplary case,the larger number of the two MinState values is used to determine thetransition out of the current state, and thus there is no need for thesignal terminating the state since both transceivers know the stateduration. However, it is to be appreciated, that based on the particularembodiment, it may be desirable to include a termination of statesignal. As in the above embodiments, this termination signal may be sentfrom the ATU-R or the ATU-C.

[0040] In operation, using the C-REVERB1 state from the example above,the ATU-R would send a message to the ATU-C indicating the minimumlength of the state of the receiver (MinState-Rx). For example, theATU-R could indicate that MinState-Rx would be equal to 2000 DMT symbolsfor C-REVERB1. Likewise, the ATU-C could send out information, such as amessage, to the ATU-R indicating the minimum length of the state of theATU transmitter (MinState-Tx). For example, the ATU-C could indicatethat MinState-Tx is equal to 1000 DMT symbols for CREVERB1. The durationof C-REVERB1 would be thus equal to the greater of the MinState-TX andMinState-Rx lengths. In this example, the length of C-REVERB1 would bechosen as the greater of the two since it was specified as being 2000DMT symbols.

[0041] In addition, it is to be appreciated that while the aboveembodiments are described in relation to forwarding a single variablestate length requirement from a first transceiver to a secondtransceiver, it is to be appreciated that it is also possible for one ormore of the transceivers to specify MinState values for a plurality ofstates in a single communication to the other transceiver. For example,the MinState values for a plurality of states could be stored in memoryand upon a determination being made to switch to a next initializationstate, the transceivers would have the necessary MinState values toensure the initialization is correctly completed for the state inquestion.

[0042] While the exemplary embodiments were described with thetransceiver 100 being ATU-C and the trancseiver 200 being the ATU-R,these could be switched such that the transceiver 200 is the ATU-C andthe transceiver 100 the ATU-R. In this alternative exemplary embodiment,the protocols and methods are used to control the length of the stateswhere the ATU-R is the transmitting transceiver and the ATU-C is thereceiving transceiver. Such an example was described above for thecontrol of the length of the R-REVERB3.

[0043]FIG. 5 illustrates an exemplary embodiment for variable statelength initialization according to this invention. In particular,control begins in step S100 and continues to step S110. In step S110, adetermination is made as to which state(s) require a minimum number ofDMT symbols. Next, in step S120, a first initialization state isselected. Then, in step S130, assuming the selected state requires aminimum number of DMT symbols, the minimum number of DMT symbols for theselected state is determined. Control then continues to step S140.

[0044] In step S140, information, such as message, specific signal oridentifier, is assembled and forwarded to a second transceiver thatspecifies the minimum number of DMT symbols for the selected state.Next, in step S150, the number of DMT symbols received or transmitted bythe second transceiver associated with the selected state is monitored.Then, in step S160, if the number of received or transmitted DMT symbolsis equal to or greater than the MinState length, control continues tostep S170. Otherwise, control jumps back to step S150.

[0045] In step S170, a determination is made as whether initializationis complete. If initialization is complete, control continues to stepS180 where initialization ends and, for example, the transceivers entersteady-state communication. Otherwise, control jumps to step S190 whereinformation, which can, for example, be a predefined signal, isforwarded to the first transceiver specifying the exit of the currentinitialization state which will allow the entry into anotherinitialization state. Control then continues back to step S130.

[0046]FIG. 6 outlines a second exemplary embodiment where both of theATU-C and the ATU-R specify a MinState value for a selected state. Inparticular, control begins in step S200 and continues to step S210. Instep S210, a determination is made as to which state(s) require aminimum number of DMT symbols (MinState). Next, in step S220, a firstinitialization state is selected. Then, in step S230, for each of theATU-C and ATU-R, the following steps are performed.

[0047] In particular, in step S240, the minimum number of DMT symbolsfor the selected state is determined. Next, in step S250, information,such as a message or identifier, is assembled and forwarded to the othertransceiver specifying the minimum number of DMT symbols for theselected state. Then, in step S260, a comparison is made between theMinState value forwarded by the ATU-R and the MinState value forwardedfrom the ATU-C and the greater of the two MinState (MaxMinState)valuesselected. Control then continues to step S270.

[0048] In step S270, each of the ATU-C and ATU-R monitor the number ofreceived or transmitted DMT symbols. Next, in step S280 a determinationis made as to whether the MaxMinState value has been met. If theMaxMinState value has been met, control continues to step S290.Otherwise, control jumps back to step S270.

[0049] In step S290, a determination is made as to whetherinitialization is complete. If initialization is complete, controlcontinues to step S300 where the control sequence ends. Otherwise,control jumps back to step S310 where the ATU-C and ATU-R switch to thenext initialization state.

[0050] The above-described initialization protocol can be implemented ona telecommunications device, such as a modem, a DSL modem, a ADSL modem,multicarrier transceiver, or the like, or on a separate programmedgeneral purpose computer having a communications device. However, thesystems and methods of this invention can also be implemented on specialpurpose computer, a programmed microprocessor or microcontroller andperipheral integrated circuit elements, an ASIC, or other integratedcircuit, a digital signal processor, a hard-wired electronic or logiccircuit, such as discrete element circuit, a programmable logic devicesuch as a PLD, PLA, FPGA, PAL, a modem, or the like. In general, anydevice capable of implementing a state machine that is in turn capableof implementing the flow charts illustrated herein can be used toimplement the variable state length initialization system according tothis invention.

[0051] Furthermore, the disclosed methods may be readily implemented insoftware using object or object-oriented software developmentenvironments that provide portable source code that can be used on avariety of computer or workstation hardware platforms. Alternatively,the disclosed variable state length initialization system may beimplemented partial or fully in hardware using standard logic circuitsor VLSI design. Whether software or hardware is used to implement thesystems in accordance with this invention is dependent on the speedand/or efficiency requirements of the system, the particular function,and the particular software or hardware systems or microprocessor ormicrocomputer systems being utilized. The variable state lengthinitialization systems and methods illustrated herein however can bereadily implemented in hardware and/or software using any know or laterdeveloped systems or structures, devices and/or software by those ofordinary skill in the applicable art from the functional descriptionprovided herein and with a general basic knowledge of the computer andtelecommunications arts.

[0052] Moreover, the disclosed methods may be readily implemented insoftware executed on a programmed general purpose computer, a specialpurpose computer, a microprocessor, or the like. In these instances, thesystems and methods of this invention can be implemented as a programembedded on a personal computer such as JAVA® or CGI script, as aresource residing on server or graphic work station, as a routineembedded in a dedicated variable state length initialization equippedreceiver transceiver or the like. The variable state lengthinitialization system can also be implemented by physicallyincorporating the system and method into a software and/or hardwaresystem, such as the hardware and software systems of a variable statelength initialization enabled transceiver.

[0053] It is, therefore, apparent that there has been provided, inaccordance with the present invention, systems and methods for variablestate length initialization. While this invention has been described inconjunction with a number of embodiments, it is evident that manyalternatives, modifications and variations would be or are apparent tothose of ordinary skill in the applicable arts. Accordingly, it isintended to embrace all such alternatives, modifications, equivalentsand variations that are within the spirit and scope of this invention.

I claim:
 1. In multicarrier communication system including a firstmulticarrier transceiver and a second multicarrier transceiver, a methodfor variable state length initialization comprising: transmitting fromthe first multicarrier transceiver to the second multicarriertransceiver information identifying a minimum number of multicarriersymbols in an initialization state; transmitting from the firstmulticarrier transceiver to the second multicarrier transceiver at leastthe minimum number of multicarrier symbols during the initializationstate; and transmitting a predefined signal from the second multicarriertransceiver to the first multicarrier transceiver allowing the firstmulticarrier transceiver to exit the initialization state and enter anew initialization state, wherein the predefined signal is sent from thesecond multicarrier transceiver to the first multicarrier transceiverafter the second multicarrier transceiver receives at least the minimumnumber of multicarrier symbols in the initialization state.
 2. Themethod of claim 1, wherein the minimum number of multicarrier symbols inthe initialization state is less than a predefined maximum number ofmulticarrier symbols for the initialization state.
 3. The method ofclaim 1, wherein the information is at least one of an identifier, asignal and a message.
 4. In a multicarrier transceiver, a method forvariable state length initialization comprising: transmitting to asecond multcarrier transceiver information identifying the minimumnumber of multicarrier symbols in an initialization state; transmittingto the second multicarrier transceiver at least the minimum number ofmulticarrier symbols during the initialization state; and receiving apredetermined signal from the second multicarrier transceiver allowingexit of the initialization state and entry into a new initializationstate, wherein the predefined signal is received from the secondmulticarrier transceiver after at least the minimum number ofmulticarrier symbols have been transmitted in the initialization state.5. The method of claim 4, wherein the minimum number of multicarriersymbols in the initialization state is less than a predefined maximumnumber of multicarrier symbols for the initialization state.
 6. Themethod of claim 4, wherein the information is at least one of anidentifier, a signal and a message.
 7. In a multicarrier transceiver, amethod for variable state length initialization comprising: receivingfrom a second multicarrier transceiver information identifying theminimum number of multicarrier symbols in an initialization state;receiving from a second multicarrier transceiver at least the minimumnumber multicarrier symbols during the initialization state; andtransmitting to the second multicarrier transceiver a predefined signalallowing exit of the initialization state and entry into a newinitialization state, wherein the predefined signal is sent to thesecond multicarrier transceiver after at least the minimum number ofmulticarrier symbols have been received in the initialization state. 8.The method of claim 7, wherein the minimum number of multicarriersymbols in the initialization state is less than a predefined maximumnumber of multicarrier symbols for the initialization state.
 9. Themethod of claim 7, wherein the information is at least one of anidentifier, a signal and a message.
 10. In multicarrier communicationsystem including a first multicarrier transceiver and a secondmulticarrier transceiver, a method for variable state lengthinitialization comprising: transmitting from the first multicarriertransceiver to the second multicarrier transceiver informationidentifying a minimum number of multicarrier symbols in aninitialization state; transmitting from the second multicarriertransceiver to the first multicarrier transceiver at least the minimumnumber of multicarrier symbols during the initialization state; andtransmitting a predefined signal from the second multicarriertransceiver to the first multicarrier transceiver indicating exit fromthe initialization state and entry into a new initialization state,wherein the predefined signal is sent from the second multicarriertransceiver to the first multicarrier transceiver after the secondmulticarrier transceiver transmits at least the minimum number ofmulticarrier symbols in the initialization state.
 11. The method ofclaim 10, wherein the minimum number of multicarrier symbols in theinitialization state is less than a predefined maximum number ofmulticarrier symbols for the initialization state.
 12. The method ofclaim 10, wherein the information is at least one of an identifier, asignal and a message.
 13. In a multicarrier transceiver, a method forvariable state length initialization comprising: transmitting to asecond multcarrier transceiver information identifying the minimumnumber of multicarrier symbols in an initialization state; receivingfrom the second multicarrier transceiver at least the minimum number ofmulticarrier symbols during the initialization state; and receiving apredefined signal from the second multicarrier transceiver indicatingexit from the initialization state and entry into a new initializationstate, wherein the predefined signal is received from the secondmulticarrier transceiver after at least the minimum number ofmulticarrier symbols have been transmitted in the initialization state.14. The method of claim 13, wherein the minimum number of multicarriersymbols in the initialization state is less than a predefined maximumnumber of multicarrier symbols for the initialization state.
 15. Themethod of claim 13, wherein the information is at least one of anidentifier, a signal and a message.
 16. In a multicarrier transceiver, amethod for variable state length initialization comprising: receivingfrom a second multicarrier transceiver information identifying theminimum number of multicarrier symbols in an initialization state;transmitting from a second multicarrier transceiver at least the minimumnumber multicarrier symbols during the initialization state; andtransmitting to the second multicarrier transceiver a predefined signalindicating exit from the initialization state and entry into a newinitialization state, wherein the predefined signal is sent to thesecond multicarrier transceiver after at least the minimum number ofmulticarrier symbols have been received in the initialization state. 17.The method of claim 16, wherein the minimum number of multicarriersymbols in the initialization state is less than a predefined maximumnumber of multicarrier symbols for the initialization state.
 18. Themethod of claim 16, wherein the information is at least one of anidentifier, a signal and a message.
 19. A variable state lengthinitialization multicarrier communication system including a firstmulticarrier transceiver and a second multicarrier transceivercomprising: means for transmitting from the first multicarriertransceiver to the second multicarrier transceiver informationidentifying a minimum number of multicarrier symbols in aninitialization state; means for transmitting from the first multicarriertransceiver to the second multicarrier transceiver at least the minimumnumber of multicarrier symbols during the initialization state; andmeans for transmitting a predefined signal from the second multicarriertransceiver to the first multicarrier transceiver allowing the firstmulticarrier transceiver to exit the initialization state and enter anew initialization state, wherein the predefined signal is sent from thesecond multicarrier transceiver to the first multicarrier transceiverafter the second multicarrier transceiver receives at least the minimumnumber of multicarrier symbols in the initialization state.
 20. Thesystem of claim 19, wherein the minimum number of multicarrier symbolsin the initialization state is less than a predefined maximum number ofmulticarrier symbols for the initialization state.
 21. The system ofclaim 19, wherein the information is at least one of an identifier, asignal and a message.
 22. A variable state length initializationmulticarrier transceiver comprising: means for transmitting to a secondmultcarrier transceiver information identifying the minimum number ofmulticarrier symbols in an initialization state; means for transmittingto the second multicarrier transceiver at least the minimum number ofmulticarrier symbols during the initialization state; and means forreceiving a predetermined signal from the second multicarriertransceiver allowing exit of the initialization state and entry into anew initialization state, wherein the predefined signal is received fromthe second multicarrier transceiver after at least the minimum number ofmulticarrier symbols have been transmitted in the initialization state.23. The system of claim 22, wherein the minimum number of multicarriersymbols in the initialization state is less than a predefined maximumnumber of multicarrier symbols for the initialization state.
 24. Thesystem of claim 22, wherein the information is at least one of anidentifier, a signal and a message.
 25. A variable state lengthinitialization multicarrier transceiver comprising: means for receivingfrom a second multicarrier transceiver information identifying theminimum number of multicarrier symbols in an initialization state; meansfor receiving from a second multicarrier transceiver at least theminimum number multicarrier symbols during the initialization state; andmeans for transmitting to the second multicarrier transceiver apredefined signal allowing exit of the initialization state and entryinto a new initialization state, wherein the predefined signal is sentto the second multicarrier transceiver after at least the minimum numberof multicarrier symbols have been received in the initialization state.26. The system of claim 25, wherein the minimum number of multicarriersymbols in the initialization state is less than a predefined maximumnumber of multicarrier symbols for the initialization state.
 27. Thesystem of claim 25, wherein the information is at least one of anidentifier, a signal and a message.
 28. A variable state lengthinitialization multicarrier communication system including a firstmulticarrier transceiver and a second multicarrier transceivercomprising: means for transmitting from the first multicarriertransceiver to the second multicarrier transceiver informationidentifying a minimum number of multicarrier symbols in aninitialization state; means for transmitting from the secondmulticarrier transceiver to the first multicarrier transceiver at leastthe minimum number of multicarrier symbols during the initializationstate; and means for transmitting a predefined signal from the secondmulticarrier transceiver to the first multicarrier transceiverindicating exit from the initialization state and entry into a newinitialization state, wherein the predefined signal is sent from thesecond multicarrier transceiver to the first multicarrier transceiverafter the second multicarrier transceiver transmits at least the minimumnumber of multicarrier symbols in the initialization state.
 29. Thesystem of claim 28, wherein the minimum number of multicarrier symbolsin the initialization state is less than a predefined maximum number ofmulticarrier symbols for the initialization state.
 30. The system ofclaim 28, wherein the information is at least one of an identifier, asignal and a message.
 31. A variable state length initializationmulticarrier transceiver comprising: means for transmitting to a secondmultcarrier transceiver information identifying the minimum number ofmulticarrier symbols in an initialization state; means for receivingfrom the second multicarrier transceiver at least the minimum number ofmulticarrier symbols during the initialization state; and means forreceiving a predefined signal from the second multicarrier transceiverindicating exit from the initialization state and entry into a newinitialization state, wherein the predefined signal is received from thesecond multicarrier transceiver after at least the minimum number ofmulticarrier symbols have been transmitted in the initialization state.32. The system of claim 31, wherein the minimum number of multicarriersymbols in the initialization state is less than a predefined maximumnumber of multicarrier symbols for the initialization state.
 33. Thesystem of claim 31, wherein the information is at least one of anidentifier, a signal and a message.
 34. A variable state lengthinitialization multicarrier transceiver comprising: means for receivingfrom a second multicarrier transceiver information identifying theminimum number of multicarrier symbols in an initialization state; meansfor transmitting from a second multicarrier transceiver at least theminimum number multicarrier symbols during the initialization state; andmeans for transmitting to the second multicarrier transceiver apredefined signal indicating exit from the initialization state andentry into a new initialization state, wherein the predefined signal issent to the second multicarrier transceiver after at least the minimumnumber of multicarrier symbols have been received in the initializationstate.
 35. The system of claim 34, wherein the minimum number ofmulticarrier symbols in the initialization state is less than apredefined maximum number of multicarrier symbols for the initializationstate.
 36. The system of claim 34, wherein the information is at leastone of an identifier, a signal and a message.
 37. A variable statelength initialization multicarrier communication system comprising: afirst multicarrier transceiver that transmits information identifying aminimum number of multicarrier symbols in an initialization state andthat transmits at least the minimum number of multicarrier symbolsduring the initialization state; and a second multicarrier transceiverthat transmits a predefined signal to the first multicarrier transceiverallowing the first multicarrier transceiver to exit the initializationstate and enter a new initialization state, wherein the predefinedsignal is sent from the second multicarrier transceiver to the firstmulticarrier transceiver after the second multicarrier transceiverreceives at least the minimum number of multicarrier symbols in theinitialization state.
 38. The system of claim 37, wherein the minimumnumber of multicarrier symbols in the initialization state is less thana predefined maximum number of multicarrier symbols for theinitialization state.
 39. The system of claim 37, wherein theinformation is at least one of an identifier, a signal and a message.40. A variable state length initialization multicarrier communicationsystem comprising: a first transceiver that transmits informationidentifying the minimum number of multicarrier symbols in aninitialization state and at least the minimum number of multicarriersymbols during the initialization state; and a predetermined signal thatis received from a second multicarrier transceiver that allows the exitof the initialization state and entry into a new initialization state,wherein the predefined signal is received from the second multicarriertransceiver after at least the minimum number of multicarrier symbolshave been transmitted in the initialization state.
 41. The system ofclaim 40, wherein the minimum number of multicarrier symbols in theinitialization state is less than a predefined maximum number ofmulticarrier symbols for the initialization state.
 42. The system ofclaim 40, wherein the information is at least one of an identifier, asignal and a message.
 43. A variable state length initializationmulticarrier transceiver comprising: a receiver portion that receivesfrom a second multicarrier transceiver information identifying theminimum number of multicarrier symbols in an initialization state and atleast the minimum number multicarrier symbols during the initializationstate; and a transmitter portion that transmits to the secondmulticarrier transceiver a predefined signal allowing exit of theinitialization state and entry into a new initialization state, whereinthe predefined signal is sent to the second multicarrier transceiverafter at least the minimum number of multicarrier symbols have beenreceived in the initialization state.
 44. The system of claim 43,wherein the minimum number of multicarrier symbols in the initializationstate is less than a predefined maximum number of multicarrier symbolsfor the initialization state.
 45. The system of claim 43, wherein theinformation is at least one of an identifier, a signal and a message.46. A variable state length initialization multicarrier communicationsystem including a first multicarrier transceiver and a secondmulticarrier transceiver comprising: a transmitter portion thattransmits from the first multicarrier transceiver to the secondmulticarrier transceiver information identifying a minimum number ofmulticarrier symbols in an initialization state and at least the minimumnumber of multicarrier symbols during the initialization state; and asecond transmitter portion that transmits a predefined signal from thesecond multicarrier transceiver to the first multicarrier transceiverindicating exit from the initialization state and entry into a newinitialization state, wherein the predefined signal is sent from thesecond multicarrier transceiver to the first multicarrier transceiverafter the second multicarrier transceiver transmits at least the minimumnumber of multicarrier symbols in the initialization state.
 47. Thesystem of claim 46, wherein the minimum number of multicarrier symbolsin the initialization state is less than a predefined maximum number ofmulticarrier symbols for the initialization state.
 48. The system ofclaim 46, wherein the information is at least one of an identifier, asignal and a message.
 49. A variable state length initializationmulticarrier transceiver comprising: a transmitter portion thattransmits to a second multcarrier transceiver information identifyingthe minimum number of multicarrier symbols in an initialization state; areceiver portion that receives from the second multicarrier transceiverat least the minimum number of multicarrier symbols during theinitialization state and a predefined signal indicating exit from theinitialization state and entry into a new initialization state, whereinthe predefined signal is received from the second multicarriertransceiver after at least the minimum number of multicarrier symbolshave been transmitted in the initialization state.
 50. The system ofclaim 49, wherein the minimum number of multicarrier symbols in theinitialization state is less than a predefined maximum number ofmulticarrier symbols for the initialization state.
 51. The system ofclaim 49, wherein the information is at least one of an identifier, asignal and a message.
 52. A variable state length initializationmulticarrier transceiver comprising: a receiver portion that receivesfrom a second multicarrier transceiver information identifying theminimum number of multicarrier symbols in an initialization state; atransmitter portion that transmits from a second multicarriertransceiver at least the minimum number multicarrier symbols during theinitialization state and a predefined signal indicating exit from theinitialization state and entry into a new initialization state, whereinthe predefined signal is sent to the second multicarrier transceiverafter at least the minimum number of multicarrier symbols have beenreceived in the initialization state.
 53. The system of claim 52,wherein the minimum number of multicarrier symbols in the initializationstate is less than a predefined maximum number of multicarrier symbolsfor the initialization state.
 54. The system of claim 52, wherein theinformation is at least one of an identifier, a signal and a message.55. An information storage media comprising information for variablestate length initialization in a multicarrier communication systemincluding a first multicarrier transceiver and a second multicarriertransceiver comprising: information that transmits from the firstmulticarrier transceiver to the second multicarrier transceiverinformation identifying a minimum number of multicarrier symbols in aninitialization state; information that transmits from the firstmulticarrier transceiver to the second multicarrier transceiver at leastthe minimum number of multicarrier symbols during the initializationstate; and information that transmits a predefined signal from thesecond multicarrier transceiver to the first multicarrier transceiverallowing the first multicarrier transceiver to exit the initializationstate and enter a new initialization state, wherein the predefinedsignal is sent from the second multicarrier transceiver to the firstmulticarrier transceiver after the second multicarrier transceiverreceives at least the minimum number of multicarrier symbols in theinitialization state.
 56. The media of claim 55, wherein the minimumnumber of multicarrier symbols in the initialization state is less thana predefined maximum number of multicarrier symbols for theinitialization state.
 57. The media of claim 55, wherein the informationis at least one of an identifier, a signal and a message.
 58. Aninformation storage media comprising information for variable statelength initialization in a multicarrier transceiver comprising:information that transmits to a second multcarrier transceiverinformation identifying the minimum number of multicarrier symbols in aninitialization state; information that transmits to the secondmulticarrier transceiver at least the minimum number of multicarriersymbols during the initialization state; and information that receives apredetermined signal from the second multicarrier transceiver allowingexit of the initialization state and entry into a new initializationstate, wherein the predefined signal is received from the secondmulticarrier transceiver after at least the minimum number ofmulticarrier symbols have been transmitted in the initialization state.59. The media of claim 58, wherein the minimum number of multicarriersymbols in the initialization state is less than a predefined maximumnumber of multicarrier symbols for the initialization state.
 60. Themedia of claim 58, wherein the information is at least one of anidentifier, a signal and a message.
 61. An information storage mediacomprising information for variable state length initialization in amulticarrier transceiver comprising: information that receives from asecond multicarrier transceiver information identifying the minimumnumber of multicarrier symbols in an initialization state; informationthat receives from a second multicarrier transceiver at least theminimum number multicarrier symbols during the initialization state; andinformation that transmits to the second multicarrier transceiver apredefined signal allowing exit of the initialization state and entryinto a new initialization state, wherein the predefined signal is sentto the second multicarrier transceiver after at least the minimum numberof multicarrier symbols have been received in the initialization state.62. The media of claim 61, wherein the minimum number of multicarriersymbols in the initialization state is less than a predefined maximumnumber of multicarrier symbols for the initialization state.
 63. Themedia of claim 61, wherein the information is at least one of anidentifier, a signal and a message.
 64. An information storage mediacomprising information for variable state length initialization in amulticarrier communication system including a first multicarriertransceiver and a second multicarrier transceiver comprising:information that transmits from the first multicarrier transceiver tothe second multicarrier transceiver information identifying a minimumnumber of multicarrier symbols in an initialization state; informationthat transmits from the second multicarrier transceiver to the firstmulticarrier transceiver at least the minimum number of multicarriersymbols during the initialization state; and information that transmitsa predefined signal from the second multicarrier transceiver to thefirst multicarrier transceiver indicating exit from the initializationstate and entry into a new initialization state, wherein the predefinedsignal is sent from the second multicarrier transceiver to the firstmulticarrier transceiver after the second multicarrier transceivertransmits at least the minimum number of multicarrier symbols in theinitialization state.
 65. The media of claim 64, wherein the minimumnumber of multicarrier symbols in the initialization state is less thana predefined maximum number of multicarrier symbols for theinitialization state.
 66. The media of claim 64, wherein the informationis at least one of an identifier, a signal and a message.
 67. Aninformation storage media comprising information for variable statelength initialization in a multicarrier transceiver comprising:information that transmits to a second multcarrier transceiverinformation identifying the minimum number of multicarrier symbols in aninitialization state; information that receives from the secondmulticarrier transceiver at least the minimum number of multicarriersymbols during the initialization state; and information that receives apredefined signal from the second multicarrier transceiver indicatingexit from the initialization state and entry into a new initializationstate, wherein the predefined signal is received from the secondmulticarrier transceiver after at least the minimum number ofmulticarrier symbols have been transmitted in the initialization state.68. The media of claim 67, wherein the minimum number of multicarriersymbols in the initialization state is less than a predefined maximumnumber of multicarrier symbols for the initialization state.
 69. Themedia of claim 67, wherein the information is at least one of anidentifier, a signal and a message.
 70. An information storage mediacomprising information for variable state length initialization in amulticarrier transceiver comprising: information that receives from asecond multicarrier transceiver information identifying the minimumnumber of multicarrier symbols in an initialization state; informationthat transmits from a second multicarrier transceiver at least theminimum number multicarrier symbols during the initialization state; andinformation that transmits to the second multicarrier transceiver apredefined signal indicating exit from the initialization state andentry into a new initialization state, wherein the predefined signal issent to the second multicarrier transceiver after at least the minimumnumber of multicarrier symbols have been received in the initializationstate.
 71. The media of claim 70, wherein the minimum number ofmulticarrier symbols in the initialization state is less than apredefined maximum number of multicarrier symbols for the initializationstate.
 72. The media of claim 70, wherein the information is at leastone of an identifier, a signal and a message.
 73. A communicationprotocol for variable state length initialization in a multicarriercommunication system including a first multicarrier transceiver and asecond multicarrier transceiver comprising: transmitting from the firstmulticarrier transceiver to the second multicarrier transceiverinformation identifying a minimum number of multicarrier symbols in aninitialization state; transmitting from the first multicarriertransceiver to the second multicarrier transceiver at least the minimumnumber of multicarrier symbols during the initialization state; andtransmitting a predefined signal from the second multicarriertransceiver to the first multicarrier transceiver allowing the firstmulticarrier transceiver to exit the initialization state and enter anew initialization state, wherein the predefined signal is sent from thesecond multicarrier transceiver to the first multicarrier transceiverafter the second multicarrier transceiver receives at least the minimumnumber of multicarrier symbols in the initialization state.
 74. Theprotocol of claim 73, wherein the minimum number of multicarrier symbolsin the initialization state is less than a predefined maximum number ofmulticarrier symbols for the initialization state.
 75. The protocol ofclaim 73, wherein the information is at least one of an identifier, asignal and a message.
 76. A communication protocol for variable statelength initialization in a multicarrier transceiver comprising:transmitting to a second multcarrier transceiver information identifyingthe minimum number of multicarrier symbols in an initialization state;transmitting to the second multicarrier transceiver at least the minimumnumber of multicarrier symbols during the initialization state; andreceiving a predetermined signal from the second multicarriertransceiver allowing exit of the initialization state and entry into anew initialization state, wherein the predefined signal is received fromthe second multicarrier transceiver after at least the minimum number ofmulticarrier symbols have been transmitted in the initialization state.77. The protocol of claim 76, wherein the minimum number of multicarriersymbols in the initialization state is less than a predefined maximumnumber of multicarrier symbols for the initialization state.
 78. Theprotocol of claim 76, wherein the information is at least one of anidentifier, a signal and a message.
 79. A communications protocol forvariable state length initialization in a multicarrier transceivercomprising: receiving from a second multicarrier transceiver informationidentifying the minimum number of multicarrier symbols in aninitialization state; receiving from a second multicarrier transceiverat least the minimum number multicarrier symbols during theinitialization state; and transmitting to the second multicarriertransceiver a predefined signal allowing exit of the initializationstate and entry into a new initialization state, wherein the predefinedsignal is sent to the second multicarrier transceiver after at least theminimum number of multicarrier symbols have been received in theinitialization state.
 80. The protocol of claim 79, wherein the minimumnumber of multicarrier symbols in the initialization state is less thana predefined maximum number of multicarrier symbols for theinitialization state.
 81. The protocol of claim 79, wherein theinformation is at least one of an identifier, a signal and a message.82. A communications protocol for variable state length initializationin a multicarrier communication system including a first multicarriertransceiver and a second multicarrier transceiver comprising:transmitting from the first multicarrier transceiver to the secondmulticarrier transceiver information identifying a minimum number ofmulticarrier symbols in an initialization state; transmitting from thesecond multicarrier transceiver to the first multicarrier transceiver atleast the minimum number of multicarrier symbols during theinitialization state; and transmitting a predefined signal from thesecond multicarrier transceiver to the first multicarrier transceiverindicating exit from the initialization state and entry into a newinitialization state, wherein the predefined signal is sent from thesecond multicarrier transceiver to the first multicarrier transceiverafter the second multicarrier transceiver transmits at least the minimumnumber of multicarrier symbols in the initialization state.
 83. Theprotocol of claim 82, wherein the minimum number of multicarrier symbolsin the initialization state is less than a predefined maximum number ofmulticarrier symbols for the initialization state.
 84. The protocol ofclaim 82, wherein the information is at least one of an identifier, asignal and a message.
 85. A communications protocol for variable statelength initialization in a multicarrier transceiver comprising:transmitting to a second multcarrier transceiver information identifyingthe minimum number of multicarrier symbols in an initialization state;receiving from the second multicarrier transceiver at least the minimumnumber of multicarrier symbols during the initialization state; andreceiving a predefined signal from the second multicarrier transceiverindicating exit from the initialization state and entry into a newinitialization state, wherein the predefined signal is received from thesecond multicarrier transceiver after at least the minimum number ofmulticarrier symbols have been transmitted in the initialization state.86. The protocol of claim 85, wherein the minimum number of multicarriersymbols in the initialization state is less than a predefined maximumnumber of multicarrier symbols for the initialization state.
 87. Theprotocol of claim 85, wherein the information is at least one of anidentifier, a signal and a message.
 88. A communications protocol forvariable state length initialization in a multicarrier transceivercomprising: receiving from a second multicarrier transceiver informationidentifying the minimum number of multicarrier symbols in aninitialization state; transmitting from a second multicarriertransceiver at least the minimum number multicarrier symbols during theinitialization state; and transmitting to the second multicarriertransceiver a predefined signal indicating exit from the initializationstate and entry into a new initialization state, wherein the predefinedsignal is sent to the second multicarrier transceiver after at least theminimum number of multicarrier symbols have been received in theinitialization state.
 89. The protocol of claim 88, wherein the minimumnumber of multicarrier symbols in the initialization state is less thana predefined maximum number of multicarrier symbols for theinitialization state.
 90. The protocol of claim 88, wherein theinformation is at least one of an identifier, a signal and a message.